1. Field of the Invention
The present invention relates a tensioner for an endless transmitting member which applies tension to the endless transmitting member to prevent the loosening of the transmitting member.
2. Description of the Prior Art
A tensioner for an endless transmitting member is known, for example, as shown in Japanese Utility Model Application Laid-Open No. 46-21307.
An endless chain for transmitting the rotation of a crankshaft of an engine to a cam shaft has a structure in which a large number of chain links are connected by pins. For this reason, if the endless chain is used over a long period, contact portions of the chain links and the pins become worn, so that the entire length of the endless chain is gradually increased. In a chain tensioner, it is necessary to compensate for the variation in tension due to the wearing and elongation of the endless chain, in addition to the variation in tension of the endless chain caused by the variation in revolution of the engine and the variation in tension of the endless chain caused by thermal expansion. For this reason, the stroke of a plunger for applying tension to the endless chain must be set at a sufficiently large value. However, if the stroke is set at a large value, there is a possibility that the endless chain may ride across the sprocket teeth when the tension of the endless chain is suddenly varied, thereby causing an incorrect meshing.